1. Field of the Invention
This invention generally relates to systems and methods for efficiently manufacturing modified asphalt materials.
2. Description of the Related Art
Conventional air-blowing of asphalt materials involves passing an oxidizing gas through the asphalt in a molten condition. In general, the effect of such conventional air-blowing is to partially oxidize the asphalt, resulting in decreased penetration and increased viscosity and softening point. However, for paving applications, such conventional air-blowing generally has a negative effect on the fatigue resistance and the low temperature properties.
U.S. Pat. No. 7,374,659, issued May 20, 2008, describes methods for making modified asphalts that involve blowing an oxygen-containing gas through a base asphalt while simultaneously subjecting the base asphalt to elevated temperatures and high levels of shear. Surprisingly, it was found that the resulting modified asphalts had both substantially improved rutting resistance and substantially improved fatigue resistance as compared to the base asphalts. Although U.S. Pat. No. 7,374,659 describes significant advances in the art, there remains a need for improved methods and systems of efficiently manufacturing modified asphalt materials on an industrial scale.